Presented as a single volume on your Mac, Fusion Drive automatically and dynamically moves frequently used files to Flash storage for quicker access, while infrequently used items move to the hard disk. As a result you'll enjoy shorter startup times, and as the system learns how you work you'll see faster application launches and quicker file access. Fusion Drive manages all this automatically in the background.

TMO's Dave Hamilton penned a detailed article about Fusion Drive following his time with Apple's hands-on session during Tuesday's media event. That article explains how and why the Fusion Drive does what it does, while Apple's FAQ looks at more basic questions.

A selection of those questions:

Do I need to configure Fusion Drive?
When ordered with a Fusion Drive, your iMac or Mac mini is pre-configured.

Can I add a Windows partition?
You can create one additional partition on the hard disk with Fusion Drive. You can create either a Mac OS X partition or a Windows partition.

If I create a hard disk partition is it part of Fusion Drive?
The additional partition is not part of Fusion Drive. The new partition is a separate volume that is physically located on the hard disk drive.

Can a Fusion Drive be mounted on another system in Target Disk Mode?
Yes, but the system attempting to mount the Fusion Drive in Target Disk Mode must have OS X Mountain Lion version 10.8.2 or later. A Fusion Drive will not appear as a Target Disk Mode volume or startup disk on earlier versions of Mac OS X.

There's more in the full article, including details on designating your startup disk and other instructions.

Most interesting announcement yesterday. I have the last generation iMac with 256GB SSD and 2TB HD. Used Terminal to set it up. Runs extremely fast, but required reasonable knowledge to set up correctly. Fusion looks to be the answer - automatically and dynamically handling the tasks I had to set up manually - and a few more I hadn’t thought of. A really cool and impressive Apple innovation. (What, Apple is still innovating?!) Be interesting to see in action - and see the benchmarks.

AppleFan20127:51 AM EDT, Oct. 25th, 2012Guest

It seems so obvious then again would be Apple the ones to bring something like this to the community. I feel like this will catch up fast, especially if it is managed by software and it does provide similar results as SSD drives. How difficult could it be to replicate this? or something with similar results

Looks like Apple has removed a part of that support article, specifically this:

“My Fusion Drive cannot see my Time Machine backups when I attempt to Restore it from a backup. What could be the issue?

If you first used a Time Machine backup drive to store images that originated from a computer with OS X Lion v10.7, you cannot select Fusion Drive backup images from the backup. Fusion Drive images must be the first ones to be written to the Time Machine backup drive to be selectable. After the initial Fusion Drive backup image is written to a Time Machine back up drive, you can add OS X Lion images to the drive and you can use it without limitations.”

It sounds different from a standard hybrid drive. In hybrid drives, the hardware decides on a block-by-block basis what blocks belong in the SDD portion and what blocks belong on the spindle drive portion. But here it seems to be done at a higher level (so the OS can say move this entire application to the SDD).

What I can’t figure out is, why? What benefit does this have over a standard hybrid drive? For example, foreign language localization files would end up on the SDD with a Fusion Drive, but would stay on the spindle with a standard hybrid (since they’re never used).